I made a start this evening on a new project building a skin on frame (sof) canoe.
the sof style originated from the Inuit of Canada and Greenland, a lightweight timber frame was built from driftwood and then skinned with sealskin, the original qajak (kayak).
The skins have now moved on with nylon or polyester woven cloth coated with a sealant of some type. The timber frames can be done in 2 ways, traditional style with steam bent ribs or a more modern style with plywood frames replacing the steam bent ribs.
Gunwales and chines (the timber that runs the length of the canoe) are usually made from western red cedar (wrc) which is very light and quite strong.
Luckily I had some wrc in the shed from another project as it’s not easy to get hold of in in “raw” planks, it’s common enough for decking but the size is not much use for this purpose.
The plywood I’m using is okoume marine ply which is made to a higher standard than regular marine ply and is built to a Lloyds of London standard.
First job today was to make the strongback, a length of 2x4 upon which the frame will be built.
Next I started ripping down the wrc for the gunwales, each gunwale will be 2 lengths laminated together for extra strength.
The canoe will be 17ft when finished so the gunwales need to be made to 18ft to allow for working them in at the bow and stern. My piece of wrc is only 12ft so I will need to scarf joint 2 pieces together to get the desired length.
Knots need to be taken out as they will crack when bending the pieces so I’ll place the scarf joints so as to keep the pieces knot free.
I cut 9 pieces off and immediately discarded 1 due to the knots. I have 4 full lengths that are knot free and 4 more that I’ll be able to use use to get the good ones up to the desired length.
I’ve made a jig for the table saw to allow me cut a 10/1 slope in the lengths, the joint will be glued with a thickened epoxy and will be very strong but a bit stiffer than the the rest of the length so I’ll have to make sure the joints are staggered to not have too many at one place on the canoe.
I don’t really have a timeframe on the build, I’ll do it as and when I get the chance.
The sof technique is not nearly as pretty or aesthetically pleasing as the strip built we had the pleasure of watching Fergal built recently but it is a lot simpler and should be lighter in weight. Target weight for the canoe is under 24kg so that it be loaded by one person, that’s a third the weight of a plastic or fibreglass canoe of the same length.
